[Significance of immunohistologic methods in the differential diagnosis of solid tumors in childhood].

We have investigated 56 histologic and 13 cytologic specimens of malignant round cell tumors of childhood. The immunohistological detection of intermediate filament polypeptides, neuron specific enolase (NSE) as well as leukocyte common antigen (LCA) allows the histological classification of such tumors. Neuroblastomas demonstrate a positive reaction with antibodies to neurofilaments and NSE independent of differentiation. Rhabdomyosarcomas could be labeled by the desmin antibody, while Ewing sarcomas, malignant lymphomas as well as nonmuscular sarcomas only express vimentin. In nephroblastomas the intermediate filament specific antibodies reveal expression of keratin and vimentin in blastema cells, while tubules are only labeled by the keratin antibody. In undifferentiated nephroblastomas, which lack formation of tubules blastema cells are keratin negative and vimentin positive. Thus antibodies to intermediate filaments, LCA and NSE seem to be useful tools to distinguish the so called "round cell tumors" of childhood.